Distinguish between DC and AC current
Electricity is nothing but electrons moving along a conductor, like a wire that has been harnessed for energy. The difference between AC and DC has to do with the direction in which the electrons flow. In DC, electrons flow steadily in a single direction. In AC, electrons keep switching directions, sometimes going forwards and then going backwards. Scientists found that electrical and magnetic fields are related. DC power was generated from the works of Thomas Edison. Nikola Tesla preferred AC because it travels farther without losing energy and could transfer different amounts of power. AC generators gradually replaced Edison's DC battery system because AC is safer to transfer over the longer city distances and can provide more power. Another difference between AC and DC involves the amount of energy it can carry. Each battery is designed to produce only one voltage, and that voltage of DC cannot travel very far until it begins to lose energy.
In a power station, electricity can be made most easily and efficiently by using a motor to spin magnetic wire coils. The resultant voltage is always "alternating" by virtue of the motor's rotation. A voltage generally goes first positive then negative rather like turning a battery cell continually backwards and forwards. Now, alternating voltage can be carried around the county in cables far more efficiently than direct current where the voltage is fixed. So the electricity that arrives at your house is still alternating voltage. Electric light bulbs and fires can run quite happily fro 230 volts A.C. Other equipment such as televisions has an internal power supply which converts the 230 volts A.C. to a low D.C. voltage that is safe and acceptable to the electronic circuits.
AC is more commonly the way of current produced in the power plants as it's easier to produce. AC is usually used for transmission because DC cannot be run through a transformer, and the distribution is quite more efficient in AC. AC can provide more power easier and with higher efficiencies than DC. In the other day a battery can only produce DC. This is why portable electrical systems use DC.
In a direct current (DC) electrical circuit, the voltage (V in volts) is an expression of the available energy per unit charge which drives the electric current around a closed circuit. Increasing the resistance will proportionately decrease the current which may be driven through the circuit by the voltage.
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Why they use words "AC","DC" (Alternating,Direct Current) for current and voltage? Why not using AV or DV?
In electrical engineering, we use the words 'AC' and 'DC' a lot. All of us know that AC stands for alternating current, and DC stands for direct current. But the strange thing is, that we use it before current and voltage. We do not say, AC when we are talking about Alternating Current, or AV when we are talking about Alternating Voltage. Instead we say 'AC current' and 'AC voltage'. This also applys for the DC. I think it is a matter of old literature, but I wonder if any one can give me the correct reason (may be historical) for this.
I am an Electrical Engineer. I ask this question seriously. Some people thought that I don't know the difference between voltage and current. This is not the question. The question is, why when we want to talk about alternating voltage we say AC voltage (alternating current voltage), when we talk about alternating current, we say AC current (alternating current current), and the same for DC. I want to know the origin of this usage in electricity. This is the same like the fact that current flows from the negative pole to the positive of the battery, not as conventionaly used in the circuit books (current flows from positive to negative). This was because the old books used this convention, and when the correct information known, they didn't change the old books and worked on the same convention because it didn't affect the calculations. This situation also in the compass, the north pole in the compass is really attracted toward the south pole, but we call that direction "North".
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Alternate & Direct Current Help!?
What is the meaning and the difference between AC / DC?
Plus-name some appliances that deals with AC or DC.
Thanks.
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